Changes in the volatiles, chemical components, and antioxidant activities of Chinese jasmine tea during the scenting processes

Figures & data

Figure 1. The chemical structures of tea catechins and methylxanthines.

Table 1. Volatile compounds identified in the aroma concentrate of basic tea, finished jasmine tea and fresh flower of J. sambac.

No.	Compounds	Relative content %
		Finished jasmine tea A	Finished jasmine tea B	Fresh flower of J. sambac	Baked green tea base
Alcohols
1	Leaf alcohol	0.82	0.59	0.25
2	Ethyl hexanol				7.94
3	Benzyl alcohol	9.17	13.07	2.56	4.21
4	Linalool oxide I	0.10	0.1	0.08
5	trans-Linalool oxide (furanoid)	0.38	0.37	0.431
6	Linalool	17.89	19.59	22.12
7	Phenylethyl Alcohol	0.10	0.09
8	Linalool oxide II (pyran)	0.14	0.14		1.60
9	α- Terpineol				1.33
10	trans-Geraniol	0.25	0.18	0.16
11	.tau.-Cadinol*	0.04	0.04	0.15
12	α-Cadinol	0.03	0.02	0.04
	Subtotal	28.92	34.19	25.79	15.08
Esters
13	cis-3-hexenyl acetate	1.24	1.06	11.79
14	Methyl benzoate	3.23	2.89	2.22
15	Benzyl acetate	24.99	24.17	16.1
16	Ethyl benzoate	0.11	0.09	0.03
17	cis-3-Hexenyl butyrate	0.24	0.14	1.33
18	Butanoic acid, hexyl ester			0.04
19	Methyl salicylate	3.55	2.34	3.48
20	cis-3-Hexenyl-α.-methylbutyrate			0.21
21	Methyl nonanoate*	0.04
22	Ethyl salicylate	0.05
23	Hexyl benzoate*	0.08	0.07	0.12
24	cis-3-Hexenyl benzoate	5.19	4.87	2.66
25	Benzyl benzoate	0.06	0.08	0.01
26	Methyl hexadecanoate	0.03
	Subtotal	38.81	35.71	37.99
N-Containing Compounds
27	Indole	5.18	6.03	0.8
28	Methyl anthranilate	5.55	5.78	1.65
29	Methyl methanthranilate	0.08	0.05
	Subtotal	10.81	11.86	2.45
Terpenes
30	β-Myrcene	0.63	0.50	0.84
31	cis-Ocimene	0.57	0.46	1.21
32	α-Cubebene	0.11	0.11	0.15
33	Copaene	0.25	0.10	0.15	4.17
34	β-Elemene	0.09		0.29
35	α-longipinene				2.40
36	(+)-Cycloisosativene				1.12
37	(+)-Sativene				1.86
38	(+)-longifolene	0.19			48.55
39	Caryophyllene	0.17	0.11	0.36	3.78
40	Aromandendrene			0.13
41	α-Caryophyllene	0.19	0.11	0.37	0.62
42	(+)-Epi-bicyclosesquiphellandrene	0.08	0.02	0.16
43	γ-Muurolene	0.16	0.1	0.32
44	Germacrene D	0.09	0.05	0.32
45	a-Muurolene	0.23	0.11	0.26
46	α-Farnesene	13.22	9.09	19.29
47	γ-Cadinene	0.40	0.25	0.72
48	δ-Cadinene	0.60	0.42	1.05	0.81
49	Cadina-1,3,5-triene*	0.13	0.10	0.17	0.70
50	Cadina-1,4-diene	0.05		0.10
51	α-Cadinene	0.08	0.05	0.23
52	α-Calacorene	0.05	0.03	0.09
53	Cadalene*	0.01
	Subtotal	17.30	11.61	26.21	64.01
others
54	Naphthalene	0.03	0.05		1.00
55	Tridecane*	0.09
56	Tetradecane	0.06	0.08		1.19
57	Butylated hydroxytoluene*	0.54	0.16		6.63
58	Eugenol	0.09	0.07
59	Hexadecane	0.03	0.03		1.45
60	Benzaldehyde		0.03		1.13
61	Pentadecane, 2,6,10-trimethyl-				0.76
62	Naphthalene, 1,2,3-trimethyl-4-propenyl-, (E)-				0.75
63	Heptadecane				0.65
64	Pentadecane, 2,6,10,14-tetramethyl-				1.08
	Subtotal	0.84	0.42		13.51
	Total	96.13	93.79	92.44	93.73

*Newly identified compounds in jasmine green tea aroma.

Figure 2. (a) Changes of total peak area of jasmine tea samples during scenting process; (b) Changes of peak area of the seven main volatile compounds in tea A during scenting process; (c) Changes of peak area of the seven main volatile compounds in tea B during scenting process; (d) JTF index of jasmine tea samples at each round of scenting process. Values were expressed as mean value (n = 3).

Table 2. Concentrations of gallic acid (mg/g DW), theobromine (mg/g DW), caffeine (mg/g DW), total soluble phenolics (TPS, mg gallic acid/g DW), and total catechins (TC, mg/g DW) during scenting process of jasmine tea A samples.

Samples	Gallic acid	Theobromine	Caffeine	TPS	TC
Base tea	1.76 ± 0.22^b	2.00 ± 0.20^a	36.69 ± 1.39^a	124.08 ± 4.36^b	90.71
A1R	1.76 ± 0.07^b	1.82 ± 0.07^a	36.76 ± 1.35^a	108.41 ± 1.71^e	88.20
A2R	1.76 ± 0.12^b	1.84 ± 0.10^a	36.70 ± 1.89^a	113.30 ± 1.49^d	89.11
A3R	1.83 ± 0.15^a	1.81 ± 0.12^a	36.92 ± 1.47^a	109.38 ± 1.62^de	90.66
A4R	1.86 ± 0.15^a	1.78 ± 0.11^a	36.59 ± 2.12^a	103.87 ± 2.42^f	89.15
A5R	1.93 ± 0.14^a	1.88 ± 0.13^a	36.83 ± 1.17^a	129.20 ± 0.26^a	88.75
A6R	1.92 ± 0.14^a	1.87 ± 0.06^a	36.97 ± 1.83^a	102.57 ± 1.87^f	89.28
Finished tea A	2.04 ± 0.14^a	1.92 ± 0.31^a	36.70 ± 3.66^a	118.58 ± 3.93^c	88.65

Values were expressed as mean ± standard deviation (n = 6).

The difference letter in the same column indicated that the difference between the grades is significantly through Duncan test (p < 0.05).

A: tea sample produced using traditional scenting technique; B: tea sample produced using modern scenting technique; 1–6 the number of the scenting rounds; R: round.

Table 3. Concentrations of gallic acid (mg/g DW), theobromine (mg/g DW), caffeine (mg/g DW), total soluble phenolics (TPS, mg gallic acid/g DW), and total catechins (TC, mg/g DW) during scenting process of jasmine tea B samples.

Samples	Gallic acid	Theobromine	Caffeine	TPS	TC
Base tea	1.76 ± 0.22^a	2.00 ± 0.20^ab	36.69 ± 1.39^b	124.08 ± 4.36^ab	90.71
B1R	1.87 ± 0.18^a	1.78 ± 0.09^a	36.80 ± 1.47^ab	116.02 ± 2.07^c	88.36
B2R	1.87 ± 0.26^a	1.89 ± 0.20^ab	36.70 ± 2.14^b	125.16 ± 1.91^a	83.37
B3R	2.01 ± 0.26^a	1.90 ± 0.03^ab	37.25 ± 1.83^ab	118.92 ± 0.95^bc	94.24
B4R	1.99 ± 0.25^a	1.90 ± 0.12^ab	36.88 ± 2.16^ab	114.49 ± 4.91^c	96.47
B5R	1.95 ± 0.12^a	1.99 ± 0.07^ab	38.77 ± 0.95^ab	115.91 ± 3.45^c	97.45
B6R	1.99 ± 0.08^a	1.96 ± 0.11^ab	38.92 ± 1.03^a	118.86 ± 2.16^bc	98.50
Finished tea B	1.98 ± 0.26^a	2.04 ± 0.09^b	38.81 ± 1.77^ab	123.86 ± 2.25^ab	96.67

Values were expressed as mean ± standard deviation (n = 6).

The difference letter in the same column indicated that the difference between the grades is significantly through Duncan test (p < 0.05).

A: tea sample produced using traditional scenting technique, B: tea sample produced using modern scenting technique, 1–6: the number of the scenting rounds, R: round.

Figure 3. Changes of EGCG, ECG, EC, GCG, GC, EGC, and C concentrations in the jasmine tea A and B samples during scenting process.Values were expressed as mean value (n = 6).

Figure 4. Changes of the antioxidant capacity of the jasmine tea samples during scenting process. Values were expressed as mean value (n = 3).